Valve gear



Aug. 7, 1928. 1,679,794

w. F. SMITH VALVE GEAR Filed Nov. 9, 1925 2 Sheets-Sheet .1

Aug. 7, 1928.

W. F. SMITH VALVE GEAR Fild Nov. 9, 1925 2 Sheets-Sheet 2 Patented Aug.7, 1928.

UNITED STATES,

PATENT WILLIAM E. :SMITH, or rouenxnnrsm, NEW YORK. ASSIG'NOR orone-Harare HERMAN A. SCHATZ, 0F POUGHKEEPSIE, NEW' YO K. 4

vALvE GEAR.

Application filed November 9, 1925. SerialNo. 67,884. I

This invention relates to new and useful improvements in. valveoperating mechanism, and more particularly to mechanism for controllingintake and exhaust valves of internal combustion engines.

The object of the invention is to p a simplevalve gear in-which thequick and accurate operation of the valves is insured and in which thevalve stems are safeguard: ed against undue strains. With this object inview I provide a mechanism in which a single lever, spring, push rod,lifter and cam are required to operate the two valves. The constructionis so provided as to permit the use. of short valvestems and relativelylong valve guides. The leverarrangement which directly bears on thevalves is .so providedthat upon the opening of either valve thereis no,resistance caused by spring pressure, eliminatingthus all side thrust onthe valve stems. tween the valve stems and the actuating lever, wherebythe objectionable noise and wear due to the hammering action issafeguarded against. A spring is used to maintain the valves closed, butthe pressure of the spring is equalized between the two valves. Wheneither valve opens, the resulting increase of pressure caused by thecompression of the spring is automatically transferred to thestationaryvalve.v Y I These and other features of the invention will more clearlyappear from the following detailed description ofa preferred emhodimentof theinvention and theappended claims. Y In the drawings a preferredembodiment of the invention is illustrated as applied to a singlecylinder internal combustionengine of. the type disclosed in mycopending applications Serial No.715',338, filed May 23, 1924 and No.722,580, filed June 26, 1924. Fig. 1 is a vertical cross-sectionofqtheen gine head illustrating the valve mechanism; Fig. 2 is ahorizontal cross-section of half, of the valve actuating mechanism alongline 2-2 of Fig. 1; Fig.8 is a top plan view of the valve actuatingmechanism, the valve box being horizontally cut away along line 3-3 ofFig. 1; Fig. 4 is a side elevation" of the cam and rocker armarrangement forming parts of thevalve gear and Figs.

5 and 6 are perspective views of details of the valve mounting. f Apiston (not shown) operating within rovide Norclearance is required beofthe lever 26 is enlarged thisTen'larged-portion is held the ball-shaped?cylinder 1 draws a mixture of airand va-.

porized gasoline from a vaporizing chamber 2.surrounding the cylinder1,;through intake passage "3 and intake port 4-into? a compressionchamber 5 provided-in. the cylinder head 6. After compressionsa'nd exaplosion,- the. residual gases. are expelled through 8 in the usualmanner. The opening and closing of the ports 4 and 7 are controlled,respectively, by intake valve 9 andexhaust valvelO. These valves areprovidedwitlr. sloping shoulders adapted to register iwith taperedseatsin the ports 4 and 7,;and with short stems, 11' and 12. The valve: stemspass through and, are vertically movable:

within guides constituted by f perforated bosses 13 and 14 in the head 6above the ports 1 exhaust port 7 and exhaust channel' 7 4 and 7." Theends of stemsll anid '12 projecting through bosses 13 and 14 areinternally screw-threaded," as indicated at 15,for l the purpose ofreceiving externally screwthreaded lugslsuch. as .16'pmjecting fromshown inFig. 5, these forked heads. are provided with perforations.through which pi ns,19 and 20 pass. The middle-portions 'forked stemheads 17 and: 18.] As clearlyof these" pins are/squared, as indicatedat,

21'inFig. 5, and are engaged. by 'jaws-22- and 23 provided at the endsof a lever" or. rocker arm 24, affording a gripping or clampingconnection between the ends *oflever 24 and the-valve stems;

The central portion of the lever 24 is enlarged, as indicated at 25.(Fig. '3), and in alignment with this enlarged portion" an arm'26projects downward substantiallyvatright angles from the lever.- Thelever" 24%" is seated in an upright collar 27 of a'cup 28 (see Figs. 1.andfi) insuch a' manner that the arm 26 projects through the collar. 27and cup 28 and the curved lower faces 29 and 30 of the lever lie withinthe notches 31 and 32 of the collar. The-ends of pin 33 projectingthrough the center of the lever 24'are seated-in the rectangular slots34-and 35 of collar 27. The cup 28 and therefore head 6 bymeans of acoiled spring. 36 .surrounding the a'rm-26, the upper. end of the thelever 24 are spaced from the'cylinder' Y spring being seatedin the cup28 andthe lower end; within a cavity 37 provided'in the 3 top ofthefcylinder head. The low'er'part' at 38 and within projection 39provided on a sleeve 40. The sleeve 40 is rigidly mounted on a shaft 41.The shaft 41 and sleeve 40 are on the outside of the cylinder headbetween the bosses 13 and 14, the contour of said space beingillustrated in Fig. 2 at 42. The sleeve is held against longitudinaldisplacement between the flat side of the cavity 42 and a nut 43provided on one end of shaft 41. The other end of the shaft projects tothe outside of the cylinder head and is there fastened to one end of acrank 44. The free end of the crank 44 carries a pin 45 which isrotatably held within a sleeve 46. A rigid arm 47 projecting from thesleeve 46 is pivoted at its free end around a bolt 48 screwed in anembossing 49 of the cylinder head. In the opposite direction an arm 50projects from the sleeve 46 and carries at'its end a clevis 51 of thepush rod.

Push rod 52 is secured to lever 50 at clevis 51. As shown in Fig. 4, thepush rod is in two sections held together by a turnbuckle 53 providedwith left and right-hand thread for the purpose of adjustment. The lowerend of the push rod is pivotally carried by a pin 54 in a boss 55provided at the end of one arm or lifter 56 of a two armed rocker 57.With its two lifters 56 and 58 carrying bosses 55 and 59, respectively,the rocker 57 straddles a cam 60. The rocker is pivotally mounted bymeans of a bolt 61 on the motor, and is surrounded by a spiral spring62, one end of which is fastened to the arm '56 at 63 and the other endto the motor at 64. The cam is rigidly mounted on the shaft 65 of acrown gear66, which meshes with a gear wheel 67 mounted on thecrankshaft 68 of the motor. 1 v I Through the gears 67 and 66 the shaft68 causes the double faced cam 60 to revolve in a clockwise direction.When the cam surface is not in contact with either roller 55 or 59, thenthe spring 62 is neutral. At this time both valves 9 and 10 are closed,being pressed against their seats by the coiled spring 36 through theagency of the lever 24.

As the cam turns to the right and moves the rocker 57 in a clockwisedirection, the spring 62 builds up tension. The tension of this springis so proportioned that at maximum speed it will overcome the inertia ofthe lifter or rocker 57, the push rod 52, and the lever 47-50. It wouldbe possible to proportion spring 36 so as to perform all this work, butif this were done the entire mechanism would be subject to the increasedpower of the spring and would increase the wear on the valve mechanism.For this reason the spring 36 is so proportioned that its tension issufiicient to operate the valve. the lever ,24 and the shaft 41. As thepush rod 52 ascends it turns through the crank 44 the shaft 41, wherebythe ball 89 is tilted to the left and through the agency of the arm 26rotates the rocker 24 in a clockwise direction around a pivot pointconstituted by the stem head 17 and pin 19. This will permit the exhaustvalve 12 to open. During the further revolution of the cam, the rockers57 and. 24 will again reach the neutral position, and then by pressureof cam 60 againstthe roller 59, an intake position will be reached inwhich the arm 24 will be tilted in the 0ppos te direct-ion from the oneillustrated in the drawing. At this time the pivot point of the arm isconstituted by the stem head 18 and pin 20.

Owing to the proper proportioning' of the two coil springs and theprovision of a single spring between the two valves, the valve stems areabout an inch and a quarter shorter than would be necessary if thesprings were appled to each valve in the usual manner. This, ofcourse,results in a saving of space, material, facilitates the manufacture, andreduces the tendency of warping of the valve stems. Furthermore, onopening either valve no resistance is offeredby spring pressure, eachvalve being free to open and close under the action of lever 24. Sincethe valve stems are lifted and permitted to dropvertically, there is noside thrust on the stems, which eliminates wear on the stems and theguides. A further feature of this construction resides 1n thepossibility of eliminating the usual clearance between the valve'stemsand the lever 24, avoiding thus the objectonable noise and wear causedby hammering action which would otherwise take place. Vith' both valvesclosed, the pressure of spring 86 is equalized between the two valves.When either valve opens, the resulting increase of pressure caused bythe compression of spring 36 is automaticallytransferred to thestationary valve wh ch will insure tight seating thereof. Owing to thiscontinuous transfer of energy from one valve to the other, the

spring 36 may be of low tension. It will be seen also that with thisconstruction, it'will be impossible for both valves to be open at thesame time, as one valve must open before the other closes. In thepresent construction the expansion of the valve stems or valves s nce,in the neutral position of the Ill) other parts does not affect theseating of the lever 24, they are always firmly held against their seat.If a clearance space were provided bet-ween the stem heads and the lever24, then such space could be easily taken up by the expansion of thestems. Owing to the absence of springs directly applied to the valvestems, fluttering of the valves at high speed is eliminated.

The operating gear of the valves is enclosed within a cas ng 60 which issecured to the cylinder head 6 by means of'bolts 60*. The cooling by airof casing 60 is facilitated by. ribs 61. In order properly to lubricatethe'valves and their 0 rating mechanism, a chamber 62 provided in. thetop of casingBO is connected at 63 with'an oil' reservoir (not shown),preferably with the crank case of.

the engine. Th chamber 62 communicates through apertures64, 65, 66 withthe valve casing 60, and owing to the pumping action of the valve stems,lubricant will be drawn into said chamber. Through the opening 65,

oil will flow. into a. cavity 67 provided in the enlarged section 25 ofrocker arm .24, andthrough a longitudinal passage 68 inarm 26, withinthe head 38 of this arm. This will supply lubricant between head 38 andthe ball 39. Oil will flow also through a channel 69 provided in theball39 into a longitudinal channel 70 provided in' shaft 41, and thenthrough a bore 71 to the bearing surface of pin 45. Oil dripping throughapertures 64 and 66 will insure lubrication of the valve said valves, alever engaging at its two ends the heads of said stems, a spring bearingagainst the centre of said lever, an arm pro- I ectmg from the centre ofsa1d lever, and

means for rocking said lever by means of said arm around pivotsconstitutedby said stem heads.

3. In an internal combustion engine, intake and exhaust valves, stemsfor said valves, a spring-pressed arm engagingat-its two ends the headsof said stems, and meansv centrally located intermediate the ends ofsaid arm for rocking said arm around pivots constituted by said stemheads.

4. In an internal combustion engine, intake and exhaust valves, stemsfor said valves, an arm engaging at its two ends the heads of saidstems, a spring. placed under tension against the centre of said arm,and means for rocking said arm around pivots constituted by said stemheads.

5, In an internal combustion engine, a cylinder head, intake and exhaustvalves therein, stems for said valves projecting through said head, anarm engaging at its two ends the heads of said stems, a spring placedunder tension between the centre of said arm and said cylinder head, andmeans for rocking said arm around pivots constituted by said stem heads.

6. A valve gear comprising two valves, stems for said valves, a leverengaging at its two ends said stems, means for alternately opening andclosing said valves through said lever, a. single spring cooperatingwiththe midpoint of said lever and placed undei tension by the valveoperating movement of said lever, and a mountingfor said spring andlever whereby the increase of pressure caused by the compressionof saidspringis transferred to the stationary one of said valves. 1 Y

:7. A valve gear comprising two valves,

stems for said valves, a single spring normally tending to maintain bothof said valves in a closed osition, a lever pivoted at its two ends insaid stems transmitting the I pressure ofsaid springthereto, .an'd meansfor rocking said lever.

8. A valve, gear comprising two valves,

stems for said valves, a single resilient means normally tending tomaintain said valves in a closed position, a lever against which saidresilient means exerts pressure, and gripping connections between theends of said lever and said stems.

9. A valve gear comprising a valve having a stem, means including alever torre ciprocating said stem, a spring bearing against said leverintermediate its ends, a gripping connection between one end of saidlever and said stem, a pivot for the other end of said lever, and meansfor moving said pivot parallel with said stem but in the oppositedirection. p

'10. A valve gear, two valves, means including a spring and a lever foroperating said valves, a cam, a lifter cooperating therewith, a push rodconnecting said lifter with saidlever, and a normally neutral springvbearing against said lifter so proportioned that when placed undertension it tends to overcome the inertia of said lifter and push rod.

the two ends of which are attached to the two valves for operating saidvalves, a spring pressing against the lever intermediate the endsthereof for normally keeping both valves closed, a cam, a liftercooperating therewith, a push rod connecting said lifter with saidlever, and a second spring placed under tension only when said camactuates said lifter.

12. A valve gear, two valves, stems for said valves, valve-operatingmechanism comprising a lever engaging at its two ends said stems, aspring bearing against the centre of said lever, ashaft for rocking said11. In a valve gear, two valves, a lever,

lever, a earn, a lifter cooperating therewith,

a push rod connecting said lifter with said shaft, and a second springopposing the movement of said'lifter, said springs being so proportionedthat they jointly tend to overcome the inertia of said valve-operatingmechanism. V

13. In a valve gear, two valves, stems for said valves, alever engagingat its two ends said stems, a spring bearing against the centre of saidlever, a shaft for rocking said lever around pivot points constituted bysaid stems, the tension of said spring being proportioned to operatesaid valves and to overcome the inertia of said lever and shaft, a cam,a lifter cooperating therewith, a push rod connecting said lifter withsaid shaft, and a normally neutral spring connected with said lifter soproportioned that when placed under tension it tends to overcome the theinertia of said lifter and push rod.

14L. In an internal combustion engine, a cylinder head, intake andexhaust valves therein, stems for said valves projecting through saidhead, a lever engaging the heads of said stems at its two ends, a springplaced under tension between the centre of said lever and the cylinderhead, "a shaft" for rocking said arm around plvot points constituted bysaid stem heads, the tension of said spring being proportioned tooperate said valves and to overcome the inertia of said lever and shaft,a cam, a lifter ceoperating therewith, a push rod connecting said lifterwith said shaft, and a normally neutral spring connected with saidlifter so proportioned that when placed under tension it tends toovercome the inertia of said lifter and push rod.

In testimony whereof, I have signed my name to this specification thisNovember, 1925.

WILLIAM F. SMITH.

2nd day of i

